Electrical coil bobbin



Jan. 21 1969 J. P. woons ET AL 3,423,711

ELECTRICAL COIL BOBBIN Original Filed Aug. 29, 1962 INVENTORS John P Woods Clifford D. Dransrie/d Henry R Barta United States Patent 3,423,711 ELECTRICAL COIL BOBBIN John 1. Woods, Anchorage, Alaska, and Clifford D. Dransfield and Henry R. Barta, Dallas, Tex., assignors to Atlantic Richfield Company, Philadelphia, Pa., a corporation of Pennsylvania Original application Aug. 29, 1962, Ser. No. 220,242, now Patent No. 3,375,574, dated Apr. 2, 1968. Divided and this application Mar. 5, 1968, Ser. No. 710,572

US. Cl. 336-192 15 Claims Int. Cl. H01f 15/10 ABSTRACT OF THE DISCLOSURE A bobbin for manufacturing magnetic transducers is made up of a generally rectangular body composed of electrically nonconductive material. The body has a mating side and a plurality of secondary sides. In one end of the body is a longitudinal aperture suitable for receiving a magnetic pole piece. In the other end is a first indentation suitable for receiving pole connecting members. Circumscribing a portion of the aperture is a second indentation in which a coil may be wound. The bobbin may include terminal pins, coil lead passageways and a sleeve for connecting the ends of the coil to external wiring.

Cross-reference to related application This is a division of copending application Ser. No. 220,242, filed Aug. 29, 1962, now Pat. No. 3,375,574 issued Apr. 2, 1968.

Background of the invention The present invention relates to a bobbin for use in manufacturing a magnetic recording and reproducing transducer of the type especially suited for operation with delay drums.

Many types of computers and automatic data processing equipment require the use of delay drums. This drum operates continuously and usually at much higher speeds than most magnetic recording systems. Under such conditions, there is a need for extremely high quality magnetic transducers of uniform characteristics. This quality and uniformity is difficult to obtain with mass production techniques.

This invention provides a bobbin which lends itself to mass production techniques to assist in assembling magnetic transducers of high quality and uniform characteristics which transducers are especially suitable for operation with high speed delay drums.

Brief description of the drawing FIGURES 1, 2 and 3 of the drawing showing isometric views of a bobbin with each view being rotated 90 about the longitudinal axis of the bobbin.

Summary of the invention This invention provides an improved bobbin for manufacturing magnetic transducers and having several or all of the features mentioned in different combinations. The bobbin is comprised of a generally rectangular shaped body composed of electrically nonconductive material. The body has first and second ends, and a mating side and a plurality of secondary sides. Extending into the first end of the body is a first aperture which is suitable for receiving a magnetic pole piece. Extending from the mating side into the body to one end of the aperture is a first indentation which is suitable for receiving pole connecting members. The first indentation will usually extend inward both from the mating side and the second end of the bobbin. Extending inward from the mating side and circumscribing a portion of the first aperture is a second indentation in which a coil of wire may be wound to encircle the first aperture. The bottom of the second indentation is separated from the first aperture preferably by a portion of the body that is approximately 0.008 inch thick. On the side of the body opposite the mating side, there may be a third indentation which is separated from the second indentation by a portion of the body. Two

passageways may extend through the portion of the body separating the third indentation from the second indentation so that the ends of coil may be passed through the passageways and connected to two terminal posts in the third indentation. The terminal posts or pins are located in two holes in the bottom of the third indentation. A second aperture may extend longitudinally inward from the second end of the body and into the third indentation. A tubular sleeve may be placed in this second aperture. Terminal wires may be passed through the sleeve and connected to the terminal pins.

Description of preferred embodiments The various features of the bobbin of this invention are illustrated in FIGURES 1 through 3 which show the bobbin in three positions as the bobbin is rotated about its longitudinal axis. The bobbin is pressure injection molded as described in copending application Ser. No. 220,242. The bobbin is made of body 11 which is composed of electrically nonconductive plastic or resinous material such as nylon, polystyrene, epoxy-type resins or the like formed in a generally rectangular configuration.

Body 11 has first end 13, second end 15 and mating side 17, which as shown in FIGURE 1 is formed by extreme top surfaces 19 and 21. Mating side 17 mates with a corresponding side or surface on a second bobbin when the bobbin is used to form a magnetic transducer. Body 11 also has a plurality of other sides with side 23 being on the opposite side of the body from mating side 17.

As shown in FIGURE 1, starting at first end 13 of the body is the first end of first aperture 25 which extends generally along a portion of the longitudinal axis of the body with the second end of the aperture between ends 13 and 15 of the body. For purposes of simplicity, tunnel or first aperture 25 is shown only in FIGURE 1.

In body 11, extending inward from mating side 17 is first indentation 27 which extends to the second end of first aperture 25 so that a magnetic pole piece may be placed into the first end of the aperture with the end of the pole piece passing through aperture 25 into first indentation 27. Preferably, as shown, first indentation 27 also extends from second end 15 of the body in order that when two bobbins are laid with their mating sides in contact, the first indentations provide a cavity for accommodating magnetic components used to cooperate with the hole pieces placed in the first apertures to complete a magnetic circuit.

Near the first end of the body is second indentation 29 which extends inward from mating side 17 and circumscribes a portion of first aperture 25. This second indentation is separaetd from first aperture 25 by part of the body and is adapted to receive coil 31 shown only in FIGURE 3. Coil 31 is made up of windings of electrically conductive wire and encircles the first aperture. Mag netic signals are passed through this coil when the bobbin is part of a magnetic transducer. For example, coil 31 may include 880 turns of enamel-covered wire of approximately ohms resistance. In order for the quality of magnetic transducer to be maintained, it is desirable that the nonconductive material in that part of the body at the bottom of second indentation 29 and separating the second indentation from the first aperture be approximately 0.008 inch thick.

On side 23 which is the side of the body opposite the mating side, there is third indentation 33 which is separated from second indentation 29 by portion 35 of body 11.

Starting at second end of the body is second aperture 37 which is separated from first indentation 27 by portion of body 11. This second aperture extends longitudinally from the second end of the body to third indentation 33. In second aperture 37 is optional tubular sleeve 39 which extends outward from second end 15 of body 11 and is used to accommodate terminal wires (not shown) that connect coil 31 with an exterior circuit. Tubular sleeve 39 is an integral part of the bobbin and is also useful in aligning two bobbins and placing the bobbins in a magnetic transducer housing.

As shown in FIGURE 3, extending longitudinally through portion 35 which separates second indentation 29 from third indentation 33 are two passageways 41 which are in communication with the second and third indentations. The two passageways are suitable for passing the two ends of coil 31 through portion 35.

Also shown in FIGURE 3, in the bottom of third indentation 33 are two pin holes 43. These pin holes extend into the body toward mating side 17 and only partially traverse the body. Inserted into the pin holes are two terminal posts or pins 45. One end of coil 31 is passed through one of passageways 41 and connected to one of the pins. The other end of coil 31 is passed through the second passageway and connected to the second of the pins. Pins 45 are also useful for connection to terminal wires (not shown) which are passed through sleeve 39. These terminal pins prevent excessive pressure or force from being applied to the delicate wires of coil 31.

As stated previously, it is preferred that the bobbins be pressure injection molded. To produce the same bobbin by potting, machining or other conventional bobbin-making operation requires excessive labor and expense. By way of example, the bobbin illustrated with the sleeve has an over-all length of approximately 0.75 inch and a maximum width of approximately 0.3 inch. The two coillead passageways and two terminal post holes can be either molded or drilled after the body is formed.

Although the bobbin described herein is suited for manufacturing a transducer which may be operated with various types of magnetic recording surfaces, it is best suited to operate with storage drums mounting metallic magnetic recording surfaces such as described in Patent No. 3,312,978. Therefore, it is to be observed that although a specific embodiment of the invention has been illustrated and described for operating with drums rotating within a certain speed range and component sizes and configurations recited therewith, various modifications and substitutions may be made, which will be obvious to those skilled in the art, without departing from the scope of the present invention which is limited only by the appended claims.

What is claimed is:

1. An improved bobbin for a magnetic transducer comprising a generally rectangular shaped body having first and second ends and composed of electrically nonconductive material, said body having a mating side and a plurality of secondary sides, a first aperture having first and second ends extending generally along a portion of the longitudinal axis of said body, said first end of said first aperture being at said first end of said body, a first indentation in said body extending from said mating side to said second end of said first aperture, and a second indentation in said body extending from said mating side and circumscribing a portion of said first aperture, said second indentation being separated by part of said body from said first aperture.

2. The improved bobbin as set forth in claim 1 wherein the nonconductive material separating bottom of the second indentation from the aperture is approximately 0.008 inch thick.

3. The improved bobbin of claim 1 wherein there is a coil of electrically conductive winding in said second indentation and circling said first aperture.

4. The improved bobbin as set forth in claim 1 wherein the second indentation extends both from the mating side and the second end of the body.

5. The improved bobbin as set forth in claim 4 wherein on the side of the body opposite the mating side there is a third indentation which is separated from said second indentation by a portion of said body.

6. The improved bobbin of claim 5 wherein in the second end of said body, there is a second aperture which is separated from said first indentation by a portion of said body, said second aperture extending longitudinally from said second end of said body to said third indentation.

7. The improved bobbin of claim 6 wherein there are two passageways extending longitudinally through the portion separating said second and third indentations, said passageways in communication with said second and said third indentations.

'8. The improved bobbin of claim 7 wherein in the bottom of said third indentation extending into said body toward said mating side there are two holes which only partial-ly traverse said body.

9. The improved bobbin of claim 8 wherein there is a pin in each of the two holes in said bottom of said third indentation.

10. The improved bobbin of claim 9 wherein there is a coil of electrically conductive winding in said second indentation and encircling said first aperture, one end of said coil passing through one of said passageways and connected to one of said pins, the other end of said coil passing through the second of said passageways and connected to the second of said pins.

11. The improved bobbin of claim 6 wherein the second aperture extends through a tubular sleeve, said sleeve extending outward from said second end of said body.

12. The improved bobbin of claim 11 wherein there are two passageways extending longitudinally through the portion separating said second and third indentations, said passageways in communication with said second and said third indentations.

13. The improved bobbin of claim 12 wherein in the bottom of said third indentation extending into said body toward said mating side there are two holes which only partially traverse said body.

14. The improved bobbin of claim 13 wherein there is a pin in each of the two holes in said bottom of said third indentation.

15. The improved bobbin of claim 14 wherein there is a coil of electrically conductive winding in said second indentation and encircling said first aperture, one end of said coil passing through one of said passageways and connected to one of said pins, the other end of said coil passing through the second of said passageways and connected to the second of said pins.

References Cited UNITED STATES PATENTS 3,215,964 11/1965 Horbach 336-198 LEWIS H. MYERS, Primary Examiner. ELLIOT A. GOLDBERG, Assistant Examiner. 

